| Water-in-oil emulsion is an environment-friendly lubricant,which is widely used in heavy load and strong impact lubrication apparatus.Gear is an importa nt basic part of mechanical equipment.The excessive wear can be prevented by adding suitable lubricants ensuring the accuracy of gear transmission.Based on the mixture model and starved lubrication model,the governing equation of water-in-oil emulsion lubrication are established.And this governing equation considers the surface tension and the degree of starved lubrication.The influences of the oil content parameters with the emulsion,tooth surface material parameters,operating parameters(load and entrainment speed),and gear geometrical parameters(modulus,pressure angle and displacement coefficient)on the oil-water emulsion lubrication properties are investigated for spur gear.The oil film stiffness and damping models was presented for spur gear.The main research contents are:1)A water-in-oil emulsion lubrication model are established,considering the surface tension and the degree of starved lubrication.The variation of oil volume fraction entering the contact area with the initial oil volum e fraction and entrainment speed are analyzed.The results show that the oil content entering the contact area increases with the improved initial oil volume fraction.The oil content decreases with the increasing entrainment speed.When the oil content de creases to the initial oil volume fraction,the oil film tend to be stable.The center thickness is positively related to the oil content entering the contact area.The film-forming ability of the emulsion is better,and the thickness of the emulsion is closer to pure oil film thickness as the oil content gets larger.Conversely,the center film thickness is closer to the film thickness in pure water lubrication.2)The water-in-oil emulsion lubrication model considering the thermal effect is established.The influences of the oil content,load and entrainment speed,radius of curvature and surface material parameters of the emulsion entering the contact area on the lubrication performances are analyzed.The lubrication characteristics of the five special meshing positions on tooth surface are analyzed for spur gear with ceramic materials.3)The transient thermal elastohydrodynamic oil-water lubrication model is established.The ceramic material is selected with the best wear resistance.The lubrication characteristics of the entire meshing cycle is analyzed.The results show that the lubrication performance is optimal when the oil content is 0.8.The increased load leads to the increase of the normal force and tangential force of the tooth surface.And it reduces the stability and lubrication performance of the gear transmission.When the rotation speed is decreased,the stability of the gear transmission is improved,but the film-forming ability of the emulsion and film thickness are reduced.As the friction of tooth surface is increased,the pressure angle and displacement coefficient are decreased.The harshness and lubrication performance are enhance d.Large modulus could improve the load-carrying capacity and the lubrication performance.4)The oil film stiffness and damping models under water-in-oil emulsion lubrication are established.The influences of oil content,curvature radius,entrainment speed,slip-to-roll ratio and load on oil film stiffness and damping are investigated.Furthermore,the oil film stiffness and damping models are applied to gear transmission.And the influences of load,speed,modulus,pressure angle and displacement coefficient on oil film stiffness and oil film damping are analyzed for spur gear. |
